Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Where did RW come from ?

There has been some recent discussion having to do with RW of fish. We can use LMB for this topic.
Where was the RW chart derived from ?
What does it factor in ? i.e. Growing season, region, feeding, genetics, pre vs post spawn etc.
There are so many factors when it comes to weigh vs. length,
I would like to discuss more from stocking to year 3, (getting the fish off to a good start) than the end result. Long term management can be for another day
You need to have a solid foundation before you get the finished product.
It seems to be common knowledge that a LMB can not sustain upwards of 140% very long, yet we are seeing percentages well above that in the first year.
Is a 12" - 1.35# closer to average in TX than it is in KS or MO ?

It was a std that was created as a management tool that depicts average weights of what started as an ever moving target of what the "AVERAGE" 100% weight ratio should be for each species through years of accumulated data from fish all over the country.
It does not mean your fish at 90% are unhealthy, just below what the std was when it all started.
The alpha and beta figures have changed on a few species over the years to make adjustments to data research trends.
It is a reference point for management and not an absolute.

That is a real good question, I was kinda wondering the same thing myself, RW is going to vary big time across the country from south to north, what may be 100% in Minn would be considered 60% in Texas and Florida, I try to take it with an average here in MO thinking that pre-spawn or post spawn is going to figure into the equation dramatically, as is coming out of a winter or going into the winter.

Jason, I believe RW is only a two-data point thing, right? It's length/weight of an actual fish compared to a statistically determined length/weight.

There's no real time factor in it unless your consider the length of the fish to be somewhat time related. I think, with feed and amped-up forage stockings, length to time comparisons wouldn't be dependable.

Would be very interesting to see some sort of data between the "normal" and the jacked-up version high forage and feeding on RW's. I think some see it on an individual basis at their own ponds but I haven't come across anything other than more single applications over the youtube saying this is the path for more trophy type stockings. No growth patterns or descriptions on what it could do for growth rates to measure against.

I don't think there's any representation on the standard RW charts for fish that are pellet feeding and/or benefiting from amped-up forage bases.

Our great aquariums....

One data point would be a pellel trained LMB @ 18.5' and 5 pounds 15 ounces.

Hybrid Crappie 16". 2.25#

Snipe's use of "average" and Sunil's use of "statistical" are a pretty good description of what standard weight is. Sunil's remark about only 2 factors (Length and Weight) is spot on. RW is just a metric that quantifies how a particular fish relates to the statistics of a particular data set. Anyways, if you were to collect information from many samples and then plotted the weight with respect to the length, you would get a scatter of points that trends higher in an obvious curved fashion. A power function fits those points best (SW = a * Length^b). That function is Standard Weight. If the plotted on log-log paper you would get a scatter of points that trend higher in linear fashion that is best fit by straight line. That log function takes the form (SW=10^(log10(a) + b*log10(length). Either equation produces identical estimates of the standard.

Lets say you divide the data into segments of length ranges. Let's say you are now looking at the range of lengths from 12.75" to 13.25". You calculate the RW for each and every fish in the group and then make a frequency plot for RW ranges. You should find that the highest frequency of occurs around RW 100 (lets say the range 95-105). The form of the frequency plot will be akin to a bell curve. Higher RW are less frequent and so are Lower RW less frequent. When your fish exceeds RW 100 then you should be able to say it is in better condition that 50% of similar length samples of the SW data set. Fish that are >140 RW are very infrequent in the sample data. When you have a sample that exceeds 140 RW it may be in better condition than 98% or more of the data set's fish of similar length fish.

But these are not the odds in your pond. If you have one sample at 140 RW then you will likely find other samples near that RW where some will be higher and others lower. In fact, it very well could be that none of your fish are less than 100RW in defiance of the standard weight sample set. RW is just a refection of the consumption that exceeded what was required by 100 RW fish. In fact it is simple to calculate. A 140 RW fish consumed 40% more in the past 12 months than a 100 RW fish consumed. It just ate more, that's all. A high average RW in a pond is an indication that food is abundant and that fish are able to store energy above the standard at their respective lengths. Because RW is primarily a function of food availability, it is not primarily anything genetic. Period.

You will probably find that high RW favors shorter fish. They often weigh less than longer fish of lower RW. This much is certain. The heavier fish consumed more. But lets consider a shorter fatter LMB and longer leaner LMB of the same weight. According to energetics, each consumed the same weight of forage. Keep in mind that a fish only has 1 mouth. Each fish has similar opportunities for encounters. All that may be different is that one is 1" longer (or shorter) than the other. The same weight on a shorter fish yields a higher RW.


A person should not read too much into areas, regional strains, etc. The standard weight curve is nothing but what it is. The most probable/frequent weight function fitted to a large dataset. Don't overcomplicate it. Use RW as means to understand trends. If your RW is higher than 100, then conditions in your pond are more favorable than the waters of the standard weight data set (that's a positive). If you notice reductions of RW, then forage additions or culling could benefit your fish and turn the tide.

With regard to region, LMB in TX require more forage than LMB in KS to grow to the same arbitrary length and weight. What is different in the South is the production of forage. It starts sooner and occurs more in a forage production growing season. TX LMB in favorable waters have more forage to eat. Something that is a good thing because TX LMB will expend more energy for maintenance than KS LMB of the same weight. This is according to energetics. Higher temperatures increase metabolism and the amount of forage that LMB need to support it.

So if in KS, if what is limiting your RW is the amount of excess forage your LMB are eating. You have three choices to improve RW. Reduce competition, increase the forage, or a combination of these two approaches. One thing is certain, it will not take as much forage consumption in KS to do the same thing. Less of the energy of forage consumed will go towards maintenance in KS and more of energy will go toward gain.

IMHO, northern waters can produce better growth than we are accustomed to but it would require some form of supplemental feeding. One needs a means to override the typical lower production of forage to accomplish greater growth. There is a lot to learn in this area. We don't yet understand how much additional forage LMB in northern waters would consume if supplemented. Right now an ongoing case study by Solitude Lake Management in a high density LMB Female only pond is providing clues. In trying to understand climate, I used Ronoke, VA. If Ronoke, VA is comparable to the climate where the pond is located, then this it located in a colder place than say Wichita, KS. They have grown Northern strain LMB to astonishing RW and Weights in only 3 years. Here are a few bullets of what they have accomplished thus far.

* Annual increase in average RW in each subsequent year
* Growth from an average weight of 1.5 lbs to an average of 6.7 lbs in three years
* An average of RW 145 in year 3
* A max RW of 165 in year 3
* A max weight of 9.25 in year 3.

The stocked females were 1 to 2 years of age at the time of stocking. There could have possibly been some 3 year old fish but these would have to be considered slow growers. Even so, even the growth of the slower growers isn't shabby.

Very nice data point esshup.

JPS - On the last bit. Those NLMB you listed are 4-6year old fish total right? Can a LMB become sexually mature in less than a year?

"You will probably find that high RW favors shorter fish." - I had wondered about this on my very small sample I posted in the other thread. I think I mentioned it as there could be something else going on. IE....6" fish don't graph on the PB spreadsheet but 7" fish do. I don't know how the sheet calculates fish that it technically doesn't graph or how much data is available to 6-7" LMB. In either case that graphed 100% RW line on the sheet is nearly vertical and there is almost no difference on the bandwidth between under and over performing fish.

If an LMB makes it 9" it is usually mature enough to mate. If this doesn't happen until Summer the following year then some will spawn at that time of year. They can in fact successfully spawn then (reference Swingle). LMB in tropical climates tend to spawn throughout the year and more than once a year. LMB in tropical climates tend to grow slower than in the southern US which is temperate in climate. They grow slower probably due to greater competition for forage that arises from more frequent spawning (of the LMB).

With regard to your spreadsheet, look at your axes and their limits. If it starts at 7, then 6" fish will not plot. Narrowing limits to a range that encompasses your data will have the effect spreading the data through the graph. This should make the data look much better in the chart.

On the age of the LMB at Solitude's managed lake in Virginia. I know that they are not all the same age. I think an estimate of 4 to 6 years of age is probably accurate (though perhaps with none of age 6). Dave Beasley, the manager, reported in a PB Magazine article that some fish were older than others. The example referenced described an older shorter fish of higher RW as compared to a heavier younger fish of lower RW. Beasley expressed an opinion that the fish with higher RW was inferior. Beasley and I are like minded regarding his analysis.

Here's the graph.

A picture paints a thousand words . OK so try this.

1. Right click on the X axis labels and select "Format Axis"
2. Change the upper limit in the Bounds section to be 0.40 lbs
3. Let us know if this helped you to view your current data better.

Don't know if anyone is interested in Beasley's remarkable pond. But I have modeled something similar in excel. Below is their stocking rate in a Tulsa located 3/4 acre pond. I use 10% for yearly mortality (which is normal for fish >1.5 lbs and less than 10 years of age. I use what I have learned from my study of energetics to predict the consumption required to balance the growth. This model assumes that morts consume as much as survivors and so the forage is a bit over estimated (between 0 and 10%). Each year is a snap shot of the population averages. The stock year is 2020 and each year thereafter is a 1 year anniversary.

By year three the average weight is 6.66 lbs and the average RW is 145. One should expect variation around those numbers. For example, Beasley had fish up to 165 RW and 9.25 lbs (NO the heaviest fish did not have the 165 RW ... I can rule that out ... it just didn't happen).



The model, based on energetics for a Tulsa climate, estimates consumption of:

1205 lbs BG in year 1 (1607 lbs/acre)
1662 lbs BG in year 2 (2217 lbs/acre)
2010 lbs BG in year 3 (2680 lbs/acre)
The model estimates that 2270 lbs of BG forage (3027 lbs/acre) could be consumed in year 4 resulting in average RW of 145, average weight of 8.38 lbs, and an average length of 21.6"

Beasley did feed other forage than BG to include GSH, Goldfish, and RBT. All of these forages are more energy dense than BG and it would require less of them. If the climate is colder at Beasley's pond it would require less weight of forage consumed ... if it is warmer, it would require more. If forage grows in the pond the consumption could exceed the stocking weights. If predators other than LMB consume stocked prey then the stocked weight might be higher than consumption. Also if stocked forage out grow the LMBs' ability to consume them, the stocking weight may be higher than consumption. So there are a few variables affecting what weight is consumed of a forage stocking of an arbitrary weight.

So what did Beasley actually feed in weight of forage each year? Beasely reports:

1100 lbs Forage in year 1
2200 lbs in year 2
2600 lbs in year 3
3000 lbs planned in year 4

Beasley's numbers are for forage stocked and this may exceed forage consumed. It's not possible to separate the slippage due to other predators, outgrowing the consumption window, stocked forage growth in situ, and climatic factors. By and large however the disagreement between forage stocking weights and the consumption required of observed gains isn't too large to be explained by a combination of those factors.

Fascinating information. Could I get a copy of that spreadsheet?

I'm currently using Bob's RW sheet and my Bass are tracking just over 100%. Have only caught 4, measured and weighed 2 of them. 15" - 1 3/4 #. I'm also tagging them for tracking.

Up until last month (when I found out about PB) I was feeding grain based Fish food by hand and not consistently. Just started to feed Aquamax MVP. My GSF and CC love it, hopefully the 150 - 4-6" BG and 50 - 4-6" HBG Hartley Fish Farms stocked yesterday will as well.

Learninboutfish,

I haven't been able post excel spreadsheets for a couple of years. Not sure if it is problem with the browser I am using, my operating system, or the PB Forum, but quit trying a long time ago. It will take some searching but I can point you to an earlier post where you can download an earlier version. We can discuss it in greater detail then. I would like to understand your goals before recommending to you how to use it.

Just an FYI, I have come under a lot of criticism here for presenting plans in excel spreadsheets. Some have gone as far as to say that such plans are entirely worthless. Elsewhere I have described what these plans are and what they are not. If you read through my history of posts you may find one where that is addressed. Not too long ago I post thoughts on the matter of planning in a thread about exceptional trophy water and climate influence. Anyways, if you are still interested after having read this FYI please feel to reach out by PM to me and we can have a conversation.

Thanks! Will do.

A little history on where WR came from. Back in the mid 1970s, two biologists by the names of R. O. Andersen and G. J. Wege published an article covering their work on LMB growth and a new statistical method that they had developed to track health of a fishery. That publication can be found here:

"Wege, G. J., and R. O. Anderson. 1978. Relative Weight (Wr): A New Index of Condition for Largemouth Bass. Pages 79-91 in G. D. Novinger and J. G. Dillard, editors. New Approaches to the Management of Small Impoundments. American Fisheries Society, North Central Division, Special Publication 5, Bethesda, Maryland."

Because this work so was well accepted for LMB, it was extended by other researchers and now Standard Weight (WS) expressions have been developed for several other species of fish.

Now, how did Anderson and Wege come up with their Standard Weight expression and how has the scientific community continued to develop these equations?

Anderson and Wege started with a simple assumed equation for fish weight: Weight = Fish Density x Length3. Since Density has units of weight divided by length3, Density times Length cubed give units of weight.

Now, Anderson and Wege sampled 18 ponds in the midwest over a period of time gathering length and weight data from hundreds, maybe thousands of LMB. They measured each fish's weight and length and sorted the data so they had data only from the upper 75th percentile of their sample lot. They then did a regression analysis on this data allowing their ficticious density value and length exponent to vary giving them a best-fit equation (line) through that data set. That best-fit becomes their Standard Weight expression (equation) for that fish with respect to its length. Their equation ended up being:

Log10(WS) = -5.316 + 3.191Log10(Total Length, mm)

In 1991 Henson took another look at the largemouth bass data and in his masters thesis provided the equation now recognized as the more accurate expression which is:

Log10 (WS) = -5.528 + 3.273Log10 (Total Length, mm)

Anderson and Wege then took their WS and defined Relative Weight (WR) equal to Actual Weight (Wact) divided by WS x 100%. When WR is equal to 100%, Wact is equal to WS and, therefore, that fish is deemed healthy.

But the overall fisheries biology crowd has looked at this a little differently. Because the calculation of WS uses only the 75th percentile of fish from a sample, pond managers generally say a fish is healthy when its WR is greater than 90%.

You can't discuss WR without talking about WS. It's really the Standard Weight chart or equation you're asking about. I'd highly suggest getting the article cited above to read the entire way they collected their samples and how they manipulated that data to get to the Standard Weight equation.

So, that's the history of WR. I hope this answered your initial question.

Terry

Prof Richard (Dick) Anderson was a friend and a Pond Boss attendee and a poster here. He has now passed on to the big fishery in the sky.

I saw this topic was brought back up so since my original post stated something about year 3. Posted is a video from the electrofishing survey we completed last month
The end of year 3 will be 9/15/26 so the fish still have all summer to grow.
The largest LMB we captured was 18.0" - 4.28#. In Calendar year 2026 we have caught 8 LMB over 4#
The video tells about the history of the pond, Stocking and current condition
I did not know this individual before the survey, he had no Idea about the pond or what had been done prior to the survey. He got all info during and after we were done
I wanted a complete unbiased opinion and he was recommended to me by Kenny Sanderson (Snipe)

Great video, Jason!

Can you come back and answer a few questions?

1.) You are north of the line where the CNBG are supposed to thrive. How are they doing in your pond?

2.) I know we are not supposed to judge genetics by the appearance of a LMB. However, your bass fingerling in the video looks like it exhibited some Florida genetics to my inexpert eye. Do you have some Florida genetics in some or all of your LMB population? If only some, did you mark them to compare their RW to the pure northern-strain LMB?

3.) Are you getting any recruitment of the SMB from Kenny's genetics in your LMB-heavy pond?


Thanks, FishinRod.

Way north, they are flourishing, have caught many over a pound and I see them in nests continuously throughout the year, there are so many that we have started culling all the 7-8” sizes
That data is showing a lot more growth and reproduction of the CNBG than the native BG
These are Northern strain, no Florida in them

I have not seen, caught or shocked up a single SMB that wasn’t originally stocked, about half of them are doing great and the other half aren’t growing well. They are centered around 2 small areas of the pond

Thanks Jason.

I think some of the CNBG did not read their own press releases. I hope you get some whoppers in your pond.

I think y'all are going to have exquisite fun at your pond over the next few years!

With respect to the CNBG. George and I and a few others found differences between CNBG from original southern sources (Fla., central/south TX , deep south) and those moved to Arkansas many generations ago from Fla.. The CNBG moved to Ark were the base sources of the many hatcheries there. Over many generations adaptation has occurred. The Ark fish appeared to have adapted to cooler waters and their traits changed somewhat. Those Ark CNBG which have been stocked even further north have continued to adapt to cooler climates. There is a thread somewhere discussing this.

Thanks ewest!